package day1205_3;

public class CirCle {
    private int  r;

    public static void main(String[] args) {
        CirCle  c=new CirCle();
        c.r=4;//半径赋值为4
        c.setR(6);//半径赋值为6
        System.out.println(c.getAread());
    }
    void setR(int r1){
        r=r1;
    }

    double  getAread(){
        return Math.PI*r*r;
    }

}
